Photonic Integrated Circuits on InP

This chapter is devoted to photonic integrated circuits (PIC) on InP semiconductor basis. This materials platform is capable of monolithically integrating not only passive optical waveguide and receiver (Rx) devices but also transmitter (Tx) type structures, in particular optical amplifiers and lasers. In the first part the principal integration approaches of these diverse device structures will be addressed: vertical integration schemes relying on evanescent optical coupling between vertically stacked device levels; and lateral integration schemes exploiting in-plane optical coupling of the optical devices. In the latter case, butt-joint coupling, selective-area-growth, and quantum-well intermixing are being used, all of them geared to accomplish lateral band gap engineering. In the following section, recent examples of PICs based on proprietary technology solutions will be given. The second part of this chapter discusses generic photonic integration copying the foundry model successfully established in the electronics world. In this model, using defined building blocks, PIC design and manufacturing are strictly separated, thereby facilitating open access to this technology. As an example of such a generic platform, the TxRx technology developed by Fraunhofer HHI will be outlined. Selected building blocks will be described, and representative PICs made on multi-project wafer runs will be shown highlighting the viability of the foundry approach. In addition, the supply chain required for successful adoption of the foundry model will be briefly covered, including the design software environment, testing and wafer validation capabilities, and also generic packaging.